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QueryProcessor iteration refinements

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skip cursor if limit < chunksize
avoid possibly volatile parameters during iteration
This commit is contained in:
Mike McLean 2011-09-20 12:50:07 -04:00
parent 1581a9603d
commit 758919f617
1 changed files with 17 additions and 6 deletions
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23
hub/kojihub.py
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@ -6269,6 +6269,9 @@ class QueryProcessor(object):
column values in query order, rather than the usual list of maps
rowlock: if True, use "FOR UPDATE" to lock the queried rows
"""
iterchunksize = 1000
def __init__(self, columns=None, aliases=None, tables=None,
joins=None, clauses=None, values=None, opts=None):
self.columns = columns
@ -6409,22 +6412,30 @@ SELECT %(col_str)s
def iterate(self):
if self.opts.get('countOnly'):
return self.execute()
elif self.opts.get('limit') and self.opts['limit'] < self.iterchunksize:
return self.execute()
else:
return self._iterate(str(self), self.values.copy(), self.opts.get('asList'))
fields = self.aliases or self.columns
fields = list(fields)
return self._iterate(str(self), self.values.copy(), fields,
self.iterchunksize, self.opts.get('asList'))
def _iterate(self, query, values, as_list=False):
def _iterate(self, query, values, fields, chunksize, as_list=False):
# We pass all this data into the generator so that the iterator works
# from the snapshot when it was generated. Otherwise reuse of the processor
# for similar queries could have unpredictable results.
cname = "qp_cursor_%s_%i" % (id(self), self.cursors)
self.cursors += 1
query = "DECLARE %s NO SCROLL CURSOR FOR %s" % (cname, self)
query = "DECLARE %s NO SCROLL CURSOR FOR %s" % (cname, query)
c = context.cnx.cursor()
c.execute(query, self.values)
c.execute(query, values)
c.close()
query = "FETCH 1000 FROM %s" % cname
query = "FETCH %i FROM %s" % (chunksize, cname)
while True:
if as_list:
buf = _fetchMulti(query, {})
else:
buf = _multiRow(query, {}, (self.aliases or self.columns))
buf = _multiRow(query, {}, fields)
if not buf:
return
for row in buf: